1. Field of the Invention
The invention relates to gas permeation membranes, and, more specifically, to switchable gas permeation membranes in which a photo-switchable low-molecular-weight liquid crystalline material acts as the active element.
2. Description of the Related Art
Polymeric membranes are currently the standard method used in many modern separation technologies. Their deployment in numerous separation processes accelerated in the 1970's as rising energy costs made energy-intensive cryogenic, thermal, and absorption-adsorption methods unattractive. Membranes based on polymeric materials operate isothermally and at low temperatures and can be tailored to provide good separation selectivity and high mass transfer (flux). Mechanisms involving flow through pores are wholly insufficient for the separation of gases such as the classic N2/02 pair, which differ in molecular diameter by only 7%. Research in the field of high-performance gas permeation membranes has, to date, focused on maximizing both flux and selectivity. The development of membranes whose permeability can be controlled during operation or tuned to respond to changes in their environment is an important goal that has yet to be realized. Such “smart” materials are in high demand for smaller-scale membrane applications such as micro-analytic and reactor devices and biomedical membranes that can be used to control drug delivery or screening.